1. Field of the Invention
The invention relates to an element for use in conjunction with a liquid sprayer or dispenser and to improvements in liquid dispensers utilizing the same for causing the liquid product to be discharged in the form of a foam rather than in the form of a stream, spray or mist. The invention is particularly useful with dispensers of the trigger-actuated type or finger pump type such as those disclosed in British Pat. Nos. 917,135, 1,315,966, and 1,331,842 and in corresponding U.S. Pat. Nos. 3,061,202, 3,685,739 and 3,650,473, respectively.
2. Description of the Prior Art
Many different forms of liquid dispensing or spraying devices have been proposed in the prior art for dispensing or spraying a variety of liquid products in the field, garden and home. Trigger type forms of such devices typically include discharge in the form of a stream, spray or mist. Special nozzle apparatus attachments in the form of elongated tips have been proposed for use with such devices that are non-foaming but otherwise are complete for converting the liquid product discharge to the form of a foam, thereby to achieve the advantages of foam spraying. Such advantages include reduced spray drift, visual evidence of spray coverage, and adherence of the product for longer periods to the surface that has been sprayed. U.S. Patents disclosing such special foam-generating nozzle attachments are U.S. Pat. Nos. 4,013,228, 3,946,947 and 3,836,076.
Such prior art foam-generating nozzle attachments are characterized by their elongation, that is by a high length-to-diameter ratio and the provision at the interface of an aspirating chamber and a passage of substantially smaller cross section of a conical or tapered surface that is positioned to be struck or impinged upon by a diverging unaerated jet of liquid product to be foamed, the foaming action depending upon the pattern of or the angle of the diverging liquid jet.
The prior art foam-generating nozzle attachments leave something to be desired from the standpoint of operation, performance, and application. Specifically, the high length-to-diameter ratio of the prior art foam-generating nozzle presents handling problems, on an assembly line, in the shipping and distribution process, and in some consumer product applications, in terms of filling, packaging and using trigger-actuated dispensers having an elongated tip. Additionally, the elongated foam-generating nozzle attachment is sensitive to variations in the internal spray pattern, and hence, to its manner of attachment to and adjustment on the dispenser since the foam is produced by impacting the diverging jet stream on a tapered wall surface. The dispensing device with such attachment also requires more effort to operate than is desirable due to the length of the attachment and the introduction of air by aspirating into an unaerated stream of liquid product. This also undesirably limits the viscosity range of liquid products that may be successfully foamed. Moreover, the foam that is produced contains less air than is required for producing the tightly packed, even foam consistency that is most economical of the product that is being dispensed.